Abstract

Purpose of Review

Functional mitral regurgitation (FMR) occurs when mitral leaflets are prevented from adequate coaptation by underlying left ventricular (LV) dysfunction, mitral annular dilation, or both. This review aims to clarify the complex clinical issues in FMR, including diagnosis and therapy.

Recent Findings

Even mild FMR has been shown to affect survival negatively. FMR is a dynamic condition and can vary within systole and with altered loading conditions. An integrative approach, including qualitative and quantitative echocardiographic data, is mandatory to determine severity of FMR. Treatment of FMR starts with guideline-directed medical therapy (GDMT) for LV dysfunction and heart failure, including cardiac resynchronization and/or revascularization, when indicated. Although mitral valve surgery may be considered in patients undergoing CABG in whom moderate or greater FMR is present, there is no convincing evidence that surgery improves outcomes. Recently, two randomized trials have compared percutaneous edge-to-edge repair of the mitral valve to GDMT. One showed striking benefit in patients with severe FMR and smaller LV volumes; the other no benefit in moderate MR with larger LV volumes.

Summary

FMR is a complex condition in which underlying LV dysfunction interrupts proper closure of the mitral leaflets. FMR can improve with GDMT for heart failure due to LV dysfunction. When it persists despite optimal titration of GDMT, transcatheter edge-to-edge mitral valve repair can improve mortality, heart failure hospitalization, and quality of life in selected patients. Trials of transcatheter mitral valve replacement are underway.

Keywords

This article is part of the Topical Collection on Secondary Prevention and Intervention

Important Advances

• Functional mitral regurgitation (FMR) is frequently present in patients with left ventricular dysfunction or heart failure and it portends a poor prognosis.

• FMR is a dynamic condition; its assessment requires an integrative approach with different imaging modalities, if necessary, and an integration between qualitative and quantitative methods.

• Definitive evidence that surgical intervention for FMR improves prognosis is lacking. Therefore, current guidelines recommend surgery as a class IIB indication (may be considered), except when the patient is undergoing CABG and also has moderate or severe FMR.

• Recent randomized trials have shown a high rate of recurrence of FMR after mitral valve repair; therefore, it is uncertain whether it is best to repair or replace the mitral valve during surgery.

• Recent trials of transcatheter edge-to-edge repair with MitraClip show striking benefit in patients with disproportionately severe FMR and no benefit in patients with lesser degrees of FMR and larger LV volumes.

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